Fluoride release and re-uptake in direct tooth colored restorative materials

Objectives. Glass ionomers may be “recharged” through topical fluoride (F −) treatments; however, this reported “recharging,” may be attributed to surface changes after F − treatment. This study examined differences in F − release and re-uptake among dual-cured and chemically-cured glass ionomers, and a photo-cured F − releasing composite. A secondary goal was to determine if tensile strength or surface roughness changed due to F − release, or F − re-uptake and re-release. Methods. In Phase 1, initial surface roughness and diametral tensile strength were measured. F − release was measured for 30 days. Strength and roughness were then remeasured. In Phase 2, surface roughness was measured, then materials were treated with a 5000 ppm neutral F − gel, the same gel without F −, or phosphoric acid. F − release was measured for 30 days, then final surface roughness and strength were determined. Results. Significant differences were found in amount and rate of F − release, and F − re-uptake and re-release among study materials and enamel controls ( p